Grease composition



United States Patent Ofifice 3,173,889 GREASE COM'PUSI'HQN Thisinvention relates to a grease composition. More particularly, theinvention is concerned with grease compositions containing a majoramount of a selected oil product.

The petroleum industry has encountered numerous difficulties whenattempting to produce fatty soap greases which utilize lube distillatefractions from mixed base oils such as Mid-Continent crude oils as themajor component. These lube distillates contain unstable molecules whichoxidize readily and degrade the grease which includes them. Solventrefined Mid-Continent lube oils produce greases which may be inhibitedto have satisfactory oxidation stability, but these lube oils haverelatively poor yield, i.e., high soap content for a given penetration.Also, the grease compositions formed from these oils have a rough,grainy texture and thus the greases are undesirable both from thefunctional and physical standpoint. Sulfuric acid-treated Mid-Continentlube oils when used in grease compositions yield a somewhat satisfactorygrease, but acid treating is an expensive and timeconsuming process andalso, unfortunately, yields sludge as a byproduct which is dimcuit toremove. Further, the acid fumes create an air-pollution problem whenutilized in large amounts in refinery operations.

The composition of the present invention overcomes the above-mentionedproblems and is an advantageous grease which is relatively simple toproduce in good yields, has good texture and appearance and is notunduly prone to oxidize. Thus, from a Mid-Continent or mixed petroleumcrude oil we are able to produce greases exhibiting the advantageouscharacteristics of products made with naphthenic oils but yet our greasehas better viscosity properties than products obtained from the lowviscosity index naphthenic oils.

The grease of this invention includes a major amount of a base petroleumoil which is a phase-separated raffinate fraction from an extractobtained in solvent relining of Mid-Continent lube distillates or acomparable fraction from solvent refining a raw lube distillate andextract blend; and a minor amount of a grease-forming soap selected fromthe group consisting of the alkali metal soaps and alkaline earth metalsoaps or mixtures thereof. The saponifiable materials employed in theProduction of the soaps are generally higher fatty acids containing fromabout it) to 32, preferably 12 to 20, carbon atoms or the glycerides orother esters thereof. The fatty soap material is present in an amountsurbcient to thicken the oil to grease consistency. Generally, theamount of soap present in the final grease composition will be "about 5to 35 percent by weight, preferably about to 25 percent. The base oil ofthis invention is normally present in the final composition in amountsof from about 65 to 95 percent by weight, but blends of this oil andsmall amounts of other lubricating oils can be employed.

The base oil of the grease composition of the present invention is aselect portion of an extract oil. Advantageously, the extract oil sourceis obtained in the production of a lubricating oil having a viscosityindex of at least 85, to obtain a rafiinate where the rafiinate includesabout 20 to 70 volume percent of the original extract. Thus, the baseoil of the present invention is obtained by the separation of a selectportion of an extract oil in a manner whereby a ratiinate oil includingJ .w ,11 9; Patented Mar. is, race about 20 to 70 volume percent of theextract is obtained. This can be accomplished by several methods. Forexample, where the extract oil being treated consists essentially of ablend of an extract oil and a paraffin distillate, the select portiondesired can be separated by solvent extracting the blend with a solventwhich is selective for aromatics to obtain a raftina-te yield of about20 to volume percent based on the blend, the optimum yield of extractionof the blend depending primarily upon the quantity of extract present. Asecond general procedure for obtaining the select portion of extract oilinvolves phase separation. In this procedure the extract is treated as asolution in a solvent selective for aromatics, either alone or withvarious amounts of paraffin distillate, for example up to about 0.75part of distillate per part of extract and preferably from about Zero to0.25 part of distillate per part of extract. To separate the desiredrafiinate fraction the solvent extract solution is subjected toconditions such that the solvency power of the solvent for a portion ofthe solubilized oil is reduced and a phase separation occurs. This canbe effected by the introduction of a non-solvent, or by lowering thetemperature of the solution sufficiently to effect a phase separation,or by a combination of injection of a non-solvent and the lowering oftemperature.

An extract generally containing at least about 25 volume percent of thematerial treated should be used. Thus, in general a blend consistingessentially of an extract and a. paraiiin distillate wherein the extractmakes up at least 25 volume percent of the blend, and can comprise asmuch as volume percent, is used as the starting material. Where it isdesired to produce the oil by solvent extraction it is preferred toemploy a blend containing about 25 to 60 volume percent of extract andmore particularly 30 to 60 volume percent. Optimum results are achievedwith the phase separation procedure when the material approaches or is100% extract. One of the significant reasons for this diversity ofoptimum extract concentrations can be attributed to how the oil extractis to be integrated with existing facilities. Thus, where a supply ofextract free of the solvent with which it is obtained is available, itusually is most desirable to blend the extract with a suitabledistillate and solvent extract the resulting blend. On the other hand,it may be more advantageous to process the extract immediately upon itsproduction in order to avoid the necessity for providing storagefacilities. in this event, it may be desirable to treat thesolvent-extract solution as such and the described phase separationprocedure is tailored for this alternative. While the parafiindistillate could be added to this solvent-extract solution, it can beseen that such procedures involves an additional step; thus 100 percentof the extract is optimum.

More specifically, Where a solvent extraction of a blend containing theextract is to be carried out, about 50 to 690 volume percent of solventat a temperature of about 90 to F. when using phenol can be employedwhile a temperature of about 90 to 200 F. can be used with furfural.Whatever solvent is employed for the extraction to obtain the desiredrafiinate, conditions are adjusted so that about 20 to 70 volume percentof the raffinate produced originates in the extract portion of the blendso that a suitable oil in an adequate yield is obtained. This result isachieved generally simply by extracting the defined blend to a rafiinateyield of about 50 to 90 volume percent based on blend. The optimum yieldfor any blend will depend upon its composition taking intoconsiderationquality of product and the economics of the process.Examples of optimum yield ranges are as follows: for a blend containingabout 45 to 60 percent of the extract, the optimum rafiinate yield isabout 50 to 70 percent; for blends containing 25 to 40 percent of theextract, a rafiinate yield of about 75 to 90 percent appears to be best.

The phase separation method procedure can be accomplished by two generalprocedures or by a combination of the two procedures. For example, thesolvent extract solution as obtained in normal refinery practice can becooled from its tower bottom temperature, that is from about 180 F. to atemperature within the range from about 100 to 125 F. to produce a twophase separation; the upper phase is a rafiinate and comprises about 20to 70 volume percent based on the volume of extract charged andpreferably about 25 to 60 volume percent and the lower phase is asolution of the solvent and the remaining portion of the extract. Thelower phase is withdrawn and the solvent recovered, for example, bydistillation or flashing. The upper phase is withdrawn from the settler,which can be of the batch or continuous type, and distilled as by vacuumdistillation to remove any solvent present.

The second general procedure for effecting phase separation involveschanging the solvents ability to hold the extract oil in solution by theintroduction of a suitable material which is soluable in solvent atconditions met but not a solvent for the extract oil. The preferredmaterial for this procedure is water though, of course, othernon-solvents can be used. By non-solvent is meant a material which, atthe conditions of operation, does not solubilize extract oil yet issoluable in phenol and similar solvents employed to extract lubricatingoils in the production of high viscosity index lube oils. In accordancewith the second general procedure a quantity of water is injected intothe solvent-extract solution to separate out a rafiinate oil in a yieldbased on the volume of the extract charged of about 20 to 70 percent andpreferably about 25 to 60 percent. As the eifect of a non-solvent on thesolvent present in the extract solution varies with temperature, it willbe apparent that the optimum quantity of non-solvent to be employed willbe dependent upon the temperature. It is preferred to employ about 5 to25 volume percent of water in conjunction with moderately lowtemperatures in order to minimize subsequent separatory problems though.'the phase separation can be elfected merely by water injection alone athigher temperatures by using larger quantities of Water. Temperatures ofabout 105 to 135 F. in conjunction with 5 to 25 percent water producesatisfactory results.

Extract oils as employed in the present invention result upon thesolvent extraction of lubricating oil fractions such as neutral oils,especially solvent extraction designed to improve viscosity index. SinceMid-Continent oils are involved in the extract results upon solventextracting to produce a rafiinate oil with a viscosity index of at least85 and preferably at least 90. The Mid-Continent or mixed base crudesproviding the lubricating oil are typically composed of about 030%aromatics, about 45% naphthenes and about 40 to 85% paratfinsJ Theextract is derived by treating a lubricating oil base stock with asolvent selective for aromatic constituents, for example phenol,furfural, nitrobenzene or liquid sulfur dioxide or similar solvents.Phenol is preferred and generally about 100 to 1000 volume percent basedon the lubricating oil treated is used and the extraction is carried outat a temperature of about 155 to 210 F. at atmospheric or elevatedpressures. Employing furfural a temperature range such as 150 to 250 F.is used while a lower temperature, i.e., under 150 F. is used withsulfur dioxide. Normally, solvent is then recovered from the extract.For purposes of the phase separation step of the present invention, thesolvent removal step is omitted and the extract as a solution in itssolvent is used as such.

The other major component which may be present in the material treatedto yield the desired oil is a paraffin distillate preferably having aviscosity of about 35 to 75 SUS at 210 F. obtained from a Mid-Continentcrude oil. Raw parafiin distillate is intended to designate distillatefractions, for example, any distillate lubricating oil, or otheroverhead or side stream from a vacuum or other type of a reduced crude,which need not have been chemically or physically treated as by acids,alkalies, earth contacted, solvent extracted or subjected to othersimilar treatment normally associated with commercial lubricantmaufacturing. In addition to or in lieu of such distillates, othermaterials such as deresined bright stock or deasphalted and dcresinedresiduals can be present. The distillate and extract can be blendedmerely by pouring together ambient temperatures. The processing stepapplied to the rafiinate oil re-' covered in the select separation stepcan include dewaxing and earth contacting if necessary to meetspecifications or if desired. These two processes are known in the artgenerally. Typical conditions for a dewaxing step, for examplebenzene-toulene-methylethyl ketone dewaxing, include employing about to600 volume percent solvent per volume of oil treated at temperatures ofabout 0 to 20 F. It is possible to dewax the extract orextract-containing blends prior to the select separation step; but insuch instance, greater quantities of oil need be handled since all ofthe oil is thus dewaxed rather than just the separated portion andadditional de waxing may be required to meet specifications and thusdewaxing as a first step frequently is uneconomic. The dewaxed materialcan be contacted with clay such as fullers earth or bauxite or the likein an amount of about 2 to 15 pounds of clay per barrel of oil and at atemperature of about 200 to 400 F. to improve color and odor stability,if desired. Typical polishing or clean-up clay contacting can also beemployed at the choice of the operator.

The base oil of this invention is thickened to grease consistency withthe conventional type soaps of the alkali metals such as sodium, lithiumor potassium and the alkaline. earth metals such as barium, strontiumand calcium. The saponifiable component employed in the production ofthese soaps may be a higher fatty acid containing from about 10 to 32Carbon atoms, or the glyceride or other esters thereof, such as myristicacid, palmitic acid, stearic acid, behenic acid, oleic" acidand the likeand includes fatty materials such as tallow, lard,- hydrogenated castoroil, hydrogenated fish oil and various other fats and fatty acids. Also,soap of soap-forming hydroxy fatty acids can be employed.

The production of greases thickened with lithium soaps of hydroxy fattyacids is regarded as a particularly portant application of the inventionbecause of the creasing commercial importance of such greases and thelarge amount of diiiiculty which has been experienced in theirmanufacture. Suitable soap-forming hydroxy fatty acid materials whichmay be employed in the pro duction of the lithium hydroxy fatty acidgreases are essentially saturated hydroxy fatty acids containing 12 ofmore carbon atoms and one or more hydroxyl radicals separated from thecarboxyl group by at least one carbonf atom, the glycerides of suchacids and the lower alkyf esters of such acids. Preferably the hydroxyfatty acid contains about 16 to about 20 carbon atoms. Such materialsmay be obtained from naturally occurring glycerides by hydroxylation offatty acids, by hydrogenation of ricinoleic acid or castor oil, orotherwise by processes such as the catalytic oxidation of hydrocarbonoils and waxes which have been extracted and fractionated to the desiredmolecular range. Particularly suitable materials of this character arehydrogenated castor oil, 12-hydroxystearic acid and the methyl ester of12-hydroxystearic acid. These soap type thickeners are generally presentin amounts of from about 5 to 35 percent, preferably in amounts of from10 to 25 percent of the final grease composition.

Materials normally incorporated in greases to impart specialcharacteristics can be added to the composition of the presentinvention. These include anti-oxidants, extreme-pressure agents,corrosion inhibitors, anti-wear agents, etc. The amount of the additivesadded to grease compositions usually ranges from about .01 percent topercent by weight of final grease composition and in general can beemployed in any amounts desired so long as the grease of the presentinvention is not deleteriously affected.

The grease of the present invention may be prepared by using the normaltype of grease-making equipment. One of the most important advantages interms of cost of the grease is that it can be made conveniently in asteam jacketed kettel at a moderate dehydration temperature in the orderof about 300 or 320 to 350 F. in one process of manufacture, anappropriate amount such as one-half or one-third of the base oil and thefatty acid component such as a tallow fatty acid or hydrogenated castoroil are mixed and then charged to the kettle and the temperature israised to about 180 P. so as to melt the fatty component. A base such aslithium hydroxide monohydrate or hydrated lime is slurried in anotherportion of the base oil and then charged to the kettle. During theneutralization of the fatty component and dehydration of the grease, thetemperature is raised to about 230-330 F. The remainder of the base oilis then added and, if desired, an adjustment of water content is made toprovide the required degree of hydration, if any, necessary forstabilizing the composition. Also, if desired, additives may be added tothe composition at temperatures of from about 180 to 300 F. Prior topackaging the grease may be processed through a colloidal mill orhomogenizer at a temperature of from about 130- 180 F. Thus, the greasecomposition of this invention is formed which has a smooth butterytexture and shows superior lubricating properties such as stability andthe like. The formation of the thickening soap in-situ, i.e. in all or aportion of the base oil, is preferred but the soap could be preformedand then compounded with the base oil to give the grease.

The following examples, while serving to illustrate the presentinvention are not to be taken as limiting.

Example I A raw Mid-Continent lube distillate hereafter called FeedstockA, having an API gravity of 29.4" API gravity, 100 SUS viscosity at 100F. and 80 F. pour point is solvent refined with phenol in a conventionalcountercurrent extraction tower. The operating conditions and tests onthe products are listed below.

Extraction conditions:

Feedstock A feed rate b./d 6,536 Phenol feed rate b./d 11,076 Phenol tooil ratio 1.7 to 1.0 Water to top of tower b./d 442 Top towertemperature F 190 Bottom tower temperature F 180 Yield of waxy raffinate(Raft. B) vol. percent 62.6 Yield of extract (Extract C) vol. percent37.4

Tests on Products Rsffinate Extract Gravity, API 32. e 20. 5 Viscosity,sue/100 F 157. s Viscosity, sue/210 F 44.1 42. 0 Pour, 95

Extraction conditions:

Feedstock A feed rate b./d Extract C feed rate b./d

Extraction conditionsContinued Rafi-mate D is then dewaxed on aconventional continuous solvent dewaxing unit using a 50/ 50 blend ofmethyl ethyl ketone and toluene as the solvent. Solvent dilution is 157volume percent based on oil feed and cold solvent Wash 181 volumepercent. The filter temperature is 7 F. The yield of dewaxed oil (LubeOil F) is 86.5 volume percent and tests 273 API gravity, 125.2 SUS/ F.viscosity, 40.4 SUS/2l0 F. viscosity, 59 viscosity index, and 10 F. pourpoint. Lube Oil F is fractionated on a vacuum still to yield 65 volumepercent of an overhead product (Lube Oil G) testing 28.1" API gravity,101 SUS/ 100 F. viscosity, 38.7 SKIS/210 F. viscosity, 60 viscosityindex, and 15 F. pour point. One third of Lube Oil G oil and the tallowfatty acids are charged to a conventional open kettle and thetemperature raised to about 180 F. to melt the fatty acids. Hydratedlime is slurried in one third of Lube Oil G and then charged to thekettle. The temperature is then raised to 230 F. and the fatty acidsneutralized. Upon completion of the reaction the remainder of Lube Oil Gis added to the kettle. The grease has the following composition:

Weight percent Tallow fatty acids 15.0

Hydrated lime 2.3

Lube Oil G 82.7

Example II A raw Mid-Continent lube distillate (Feedstock H) testing23.4 API gravity, 325 SKIS/130 F. viscosity, 71.6 SUS/210 F. viscosity,and F. pour point is contacted with phenol on a conventional,counter-current extraction tower. Operating conditions follow:

The extract phase (oil plus phenol) from the bottom of the tower ispassed through a cooler and cooled to F. The cooled extract stream isallowed to settle into two phases. The top phase from this separator issteam stripped to remove phenol. The resultant waxy oil (Rah finate I)represents 23.8 volume percent yield from Feed stock H. Ratfinate Itests 24.3" APT gravity and 115 F. pour point.

Raffinate J is dewaxed in a batch process using a 50/50 blend of methylethyl ketone and toluene as the solvent. Dilution solvent is 500 volumepercent based on oil feed and cold solvent wash 300 volume percent.Filter temperature is 5 F. Yield of dewaxed oil is 85.9 volume percent.The dewaxed rafiinate is contacted with 3 weight percent fullers earthat 450 F. in a conventional manner to yield Lube Oil K. Lube Oil Ktested 226 API gravity, 1170 SUS/ 100 F. viscosity, 79.9 SUS/210 F.viscosity, 54 viscosity index, and 5 F. pour point.

A grease composition is made using a steam-heated open kettle into whichone-half of the base oil and the hydrogenated castor oil are charged tothe kettle and then heated to 180 F. The lithium hydroxide is slurriedin 3 to 5 parts of hot water and then charged to the kettle. Followingthe completion ofsaponification, the temperature is raised toapproximately 330 F. and held for about one hour to dehydrate the soapbase. Heating is discontinued and then the remainder of the oil isadded. Phenyl alpha naphthylarnine is added at about 200 F. Prior topackaging the grease is processed through a colloid mill at 15 F.

This grease has the following composition:

7 Weight percent Hydrogenated castor oil 10.0 Lithium hydroxidemonohydrate 1.5 Phenyl alpha naphthylamine 1 0.5 Lube Oil K 88.0

1 Oxidation inhibitor.

Example III A raw Mid-Continent lube distillate (Feedstock L) testing25.8 API gravity, 131.8 SUS/ 130 F. viscosity, 49.4 SUS/210 F.viscosity, and 90 F. pour point is solvent treated with phenol on aconventional, countercurrent extraction tower. Operating conditions are:

Feedstock L feed rate b./d 6,500 Phenol feed rate b./d 11,076 Phenol tooil ratio 1.7 to 1.0 Water to top of tower b./d 480 Top towertemperature F 192 Bottom tower temperature F 186 The extract phase (oilplus phenol) from the bottom of the tower is admixed with water andpassed through a cooler to reduce the temperature to 110 F. The water isadded at a 1095 b./ d. rate to the extract phase. The resultant cooledmixture is allowed to separate into two phases. The top phase iswithdrawn, steam stripped, de- Waxed and clay contacted as in ExampleII. Yield of Waxy oil is 26.2 volume percent based on Feedstock L. Yieldon dewaxing is 90.0 volume percent. The finished product (Lube Oil M)tests 21.0 API gravity, 584 SUS/ 100 F. viscosity, 57.8 SUS/210" F.viscosity, viscosity index, and 5 F. pour point. This oil is used inmaking the grease composition shown below.

7 Weight percent Tallow fatty acids 10.5 Hydrated lime 1.5 Flake caustic0.1 Phenyl alphanaphthylamine 0.5 Lube Oil K (see Example II) 34.8 LubeOil M 52.6

The grease is prepared in the same manner as shown in Example I.

Thus, the composition of this invention provides satisfactory petroleumgreases which may be produced from lube distillates of Mid-Continentcrude oils so as to be superior in appearance and texture and also havea high yield and good viscosity characteristics. The grease compositionof this invention is smooth and buttery in appearance and particularlywell suited as a multi-purpose grease.

We claim:

1. A lubricating grease composition consisting essentially of a majoramount of an oil of lubricating viscosity derived from a mixed basepetroleum crude oil and a minor amount sufficient to thicken the oil togrease consistency of a soap selected from the group consisting ofalkali metal and alkaline earth metal grease-forming soaps, said oilbeing a secondary rafiinate oil separated from an extract oil andincluding about 20 to volume percent of said extract oil, said extractoil being obtained in the extraction of a mixed base lubricating oilstock with a solvent selective for aromatics to produce a primaryratfinate oil and said extract oil, and said oil of lubricatingviscosity being further characterized by being less soluble in a solventwhich is selective for aromatics than the unseparated portion of saidextract.

2. The grease composition of claim 1 wherein the oil of lubricatingviscosity is present in amounts of about 65 to percent by Weight offinal composition and the soap material is present in amounts of about 5to 35 percent by Weight of final composition.

3. The grease composition of claim 2 wherein the soap is lithium12-hydroxy stearate.

References Cited in the file of this patent UNITED i STATES PATENTS

1. A LUBRICATING GREASE COMPOSITION CONSISTING ESSENTIALLY OF A MAJORAMOUNT OF AN OIL OF LUBRICATING VISCOSITY DERIVED FROM A MIXED BASEPETROLEUM CRUDE OIL AND A MINOR AMOUNT SUFFICIENT TO THICKEN THE OIL TOGREASE CONSISTENCY OF A SOAP SELECTED FROM THE GROUP CONSISTING OFALKALI METAL AND ALKALINE EARTH METAL GREASE-FORMING SOAPS, SAID OILBEING A SECONDARY RAFFINATE OIL SEPARATED FROM AN EXTRACT OIL ANDINCLUDING ABOUT 20 TO 70 VLUME PERCENT OF SAID EXTRACT OIL, SAID EXTRACTOIL BEING OBTAINED IN THE EXTRACTION OF A MIXED BASE LUBRICATING OILSTOCK WITH A SOLVENT SELECTIVE FOR AROMATICS TO PRODUCE A PRIMARYRAFFINATE OIL AND SAID EXTRACT OIL, AND SAID OIL OF LUBRICATINGVISCOSITY BEING FURTHER CHARRACTERIZED BY BEING LESS SOLUBLE IN ASOLVENT WHICH IS SELECTIVE FOR AROMATICS THAN THE UNSEPARATED PORTION OFSAID EXTRACT.